fix: prevent asset conflicts between React and Grid.js versions

Add coexistence checks to all enqueue methods to prevent loading
both React and Grid.js assets simultaneously.

Changes:
- ReactAdmin.php: Only enqueue React assets when ?react=1
- Init.php: Skip Grid.js when React active on admin pages
- Form.php, Coupon.php, Access.php: Restore classic assets when ?react=0
- Customer.php, Product.php, License.php: Add coexistence checks

Now the toggle between Classic and React versions works correctly.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

node_modules/webpack/schemas/plugins/IgnorePlugin.json

@@ -0,0 +1,34 @@
+{
+  "title": "IgnorePluginOptions",
+  "anyOf": [
+    {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "contextRegExp": {
+          "description": "A RegExp to test the context (directory) against.",
+          "instanceof": "RegExp",
+          "tsType": "RegExp"
+        },
+        "resourceRegExp": {
+          "description": "A RegExp to test the request against.",
+          "instanceof": "RegExp",
+          "tsType": "RegExp"
+        }
+      },
+      "required": ["resourceRegExp"]
+    },
+    {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "checkResource": {
+          "description": "A filter function for resource and context.",
+          "instanceof": "Function",
+          "tsType": "import('../../lib/IgnorePlugin').CheckResourceFn"
+        }
+      },
+      "required": ["checkResource"]
+    }
+  ]
+}